1. Field of the Invention
This invention relates to improvements in liquid dispensing containers or devices of the type wherein a pressurizable chamber, contained within the device, is charged with liquid from a receptacle or reservoir also carried in the device. More particularly, this invention relates to improvements in rechargeable dispensers of the type referred to wherein means is provided for (a) insuring a full charge in the pressurizable chamber as long as there is liquid in the receptacle (b) a more precise liquid shut-off at the end of discharging by relieving liquid pressure in the charge chamber just prior to the end of discharging, and (c) positive indication of the end of the charging cycle of stroke.
2. Description of the Prior Art
Various types of liquid dispensers, spraying devices or sprayers have been proposed for discharging liquids in a spray from a container to eliminate prepressurization with propelling gases and the like as in aerosol atomizing sprayers. Among such prior art dispensers is a manually operated, rechargeable sprayer described in a co-owned to Carl E. Malone U.S. Pat. No. 3,471,065, issued Oct. 7, 1969, which has two telescoping parts surrounding an inner chamber which is to be charged with liquid. Charging of the inner chamber is accomplished by forcefully pushing or pulling the telescoping parts, the force being directly linearly applied in a pumping action. This pumping action compresses a spring and simultaneously causes liquid to be drawn into the charge chamber. The piston urged by the compressed spring pressurizes the liquid in the chamber which also closes a check valve positioned at the entrance to the chamber. A discharge valve is also provided to release the liquid by discharging it through a nozzle mounted above the discharge valve.
Other types of rechargeable liquid dispensing devices are also known to the art wherein one part is rotated relative to another part to reciprocate a piston in a cylinder to define a pressurizable liquid containing chamber therebetween. The liquid in the pressurizing chamber is maintained under hydraulic pressure by a spring as in the previously described telescoping parts device. Examples of this type of dispenser aredisclosed in U.S. Pat. No. 3,790,034, issued Feb. 5, 1974, U.S. Pat. No. 3,792,800 to Nicholas G. Capra et al., issued Feb. 19, 1974, and U.S. Pat. Nos. 3,746,261, 3,777,945, 3,797,748, and 3,799,448 all to T. Nozawa et al., and issued on July 17, 1973, Dec. 11, 1973, Mar. 19, 1974 and Mar. 26, 1974 respectively. These patents disclose rechargeable sprayers wherein a biasing member or restoring spring is compressed by rotating one part of the device relative to another part, to "cock" the same. At the same time liquid is drawn into a pressurizable chamber formed by the piston vacating the cylinder in which it reciprocates. The liquid is thereafter subjected to hydraulic pressure developed by the compressed spring. First issued Nozawa et al U.S. Pat. No. 3,746,261 discloses a cocking mechanism of this type using a ball-in-track system to convert rotary motion to reciprocating. In second issued Nozawa et al U.S. Pat. No. 3,777,945 is described a similar device with the rotating parts being a two-piece press-on cap and a container with an inner, transverse wall which defines an auxiliary sump or chamber in which liquid under pressure can be stored prior to discharge. Third issued Nozawa et al U.S. Pat. No. 3,797,748 discloses a similar device but with a rigid discharge conduit leading from the pressure chamber to a discharge nozzle. Last issued Nozawa et al U.S. Pat. No. 3,799,448, discloses a similarly operating sprayer but has incorporated therewith various valving devices or means to effect precise liquid discharge flow shut-off.
Other prior art, in particular, also co-owned, U.S. Pat. No. 3,779,464 to Carl E. Malone, issued Dec. 18, 1973, discloses a fingertip pump sprayer adapted to be mounted on a liquid container which features a ball check valve and associated piston, the valve being alternately opened and closed during pumping. An added feature is an anti-dribbling device on the piston which contacts the ball to dislodge it at the end of a piston discharge stroke.
Still other prior art pump sprayers are known, also hand-held, manually operated trigger devices. These all have the common disadvantage of requiring continual and/or rapid application of force for continued spraying rather than, as in the present invention, a single cocking action to produce a steady stream of liquid over a predetermined period of time. These trigger devices enjoy relatively wide spread usage possibly because of their relatively low cost which may compensate in some measure for their inherent disadvantages which are; poor spray rate control, poor atomization and a requirement to expend more physical effort to operate.
In contrast, rechargeable dispensers of the type represented by the present invention are capable of producing constant spray rates under controlled conditions for predetermined durations. The advantages of the present invention over U.S. Pat. No. 3,471,065 above mentioned, are less effort to operate since the latter requires a relatively high cocking force to charge the liquid to the pressure chamber and smaller size or package while maintaining the same, or even increased volume of liquid spray. The rotating parts rechargeable sprayer, as disclosed in above mentioned U.S. Pat. Nos. 3,790,034 through 3,799,448, while resolving the dimensional and cocking force problems of U.S. Pat. No. 3,471,065, have other deficiencies, e.g., no way to positively determine the end of a charging cycle, and/or to insure a full charge is present in the chamber. U.S. Pat. No. 3,799,448, while disclosing several ways to produce precise spray shut-off, accomplishes the same less economically using complicated structure and, in addition, lacks the capability of insuring a full charge in the chamber before pressurization.
These disadvantages of the above and other prior art rechargeable dispensing containers are believed overcome by the present invention.